Dynamic batch experiments were carried out for the biosorption of basic yellow dye on to the green macroalgae Caulerpa scalpelliformis. The
factors affecting the sorption process such as the initial concentration of the dye and pH of the solution, the adsorbent dosage and the time of contact
were studied. The sorption kinetics followed pseudo-second order kinetic model. The Caulerpa species exhibited a maximum uptake of 27 mg of
dye per gram of seaweed. The Boyd’s plot confirmed the external mass transfer as the rate-limiting step. The average effective diffusion coefficient
was found to be 2.47×10−4 cm2/s. Sorption equilibrium studies demonstrated that the biosorption followed Freundlich isotherm model, which
implies a heterogeneous sorption phenomenon. Various thermodynamic parameters such as enthalpy of sorption H◦, free energy change G◦
and entropy S◦ were estimated. The negative value of H◦ and negative values of G◦ show the sorption process is exothermic and spontaneous.
The negative value of entropy S◦ shows the decreased randomness at the solid–liquid interface during the sorption of dyes onto green seaweed.
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